As some of you are aware, it seems that I have been running on 5 cylinders for a while now. The problem seems to be with the 2nd injector or the wiring to it. The coil, plug and connection to the coil have been checked and there are no problems there (get a big fat juicy spark). However the plug is not very wet :( . The injector has a 12v constant running to it but, I'm not sure how to test the pulse (i.e. the earth wire). I have rewired the Traction Control on Sunday but it seems that connection 110 on the ECU (which is the 2nd injector) was a nice firm connection. I will be by passing the TC tonight if I have time. Then Ican hopefully eliminate the Traction Control from being the problem.

 

I'll also test the ECU injector wires for resistance. I have been told it should be around 15 Ohms.

 

What's the easiest way to test the earth to the injector under the bonnet ?, as if the ECU is ok, I can then eliminate the wiring completely and change the injector.

 

Andy P was a great help again on Saturday evening/night. Thanks again for your time Andy.

Had a chat with Mike Feeney and he did suggest trying some injector cleaner. The plug was not completely dry, so that may help if the injector is partially blocked.

 

IIRC all the injectors are connected back to pin 58 on the ECU, you could test each one back to that point.

hiya bud.

 

check the resistance across the injector as you say. to check the wiring, test for continuity down the earth wire at the plug & at the control unit (disconnected from the ecu), you can also check for short to earth & + in case its shorted out along its length.

 

you can also get a tester called a noid lamp, which goes in the connector to check for pulse which may help in diagnosis.

 

give us a ring if you need any more advise - my vehicle electic skills are a lot better than my bowling ;)

Originally posted by AndyP

IIRC all the injectors are connected back to pin 58 on the ECU, you could test each one back to that point.

 

andy - looking at the wiring, pin 58 is a 12v feed to both the injectors & the ecu, so it should be ok on that side anyway

Funny you should mention injector cleaner, because I actually bought some of this yesterday thinking that it may just be clogged.

I bought the stuff you bung in the petrol tank. STP stuff it was. I've not put it in yet as I only have half a tank in there, so I'll do this tonight when I top it up. Is the STP stuff any good or would you recommend something else ?. If it is clogged then I guess I'll need a three of four tank cycles of the stuff, or do I need to do these cycles every other tank worth (if you see what I mean).

 

When I looked at the wiring diagram it says that 58 the 12v constant live as Paul says which we checked (when you almost electrocuted yourself remember) :D . The pulse or earth wire for injector 2 is apparently port 110.

Correct me if I'm wrong. This is where I looked for the info. http://www.300zx.co.uk/tech/manual/manual/eccsdiag/001.gif

 

Paul, I don't quite understand this bit:

check the resistance across the injector as you say. to check the wiring, test for continuity down the earth wire at the plug & at the control unit (disconnected from the ecu), you can also check for short to earth & + in case its shorted out along its length.

How do I check this ?, I have a multimeter but I'm better at 10 pin bowling than I am with one of these things ;).

Where can I get a noid lamp ?.

Thanks for that confirmation, as I said it was from memory !

 

Originally posted by Paul C

andy - looking at the wiring, pin 58 is a 12v feed to both the injectors & the ecu, so it should be ok on that side anyway

Working on the basis that stronger is probably better I'd put it in a half empty tank I think, especially as the Zed has quite a large tank anyway. Mike did say that he'd had some very good results with this, sometimes in a very short period of time, didn't say what type he used though, but I'd guess they all use a similar solvent.

 

 

Originally posted by smw1

Funny you should mention injector cleaner, because I actually bought some of this yesterday thinking that it may just be clogged.

I bought the stuff you bung in the petrol tank. STP stuff it was. I've not put it in yet as I only have half a tank in there, so I'll do this tonight when I top it up. Is the STP stuff any good or would you recommend something else ?. If it is clogged then I guess I'll need a three of four tank cycles of the stuff, or do I need to do these cycles every other tank worth (if you see what I mean).

ok, 1st disconnect the connectors from the injector & ecu, set the meter to ohms & insert into pin 110 in the ecu connector & the same wire at the injector connector. this is checking the continuity down the wire, should be nice & low around 1ohm.

 

then connect 1 of your probes to a good earth & leave the other probe in 1 end of the wire, should be open circuit other wise the wire has cut through & shorted to earth.

 

then set you meter to volts. 1 probe in wire & other to good earth. should be 0v, other wise shorted through to another wire (short to +) test with ign on. - least likely

 

:)

Have had exactly the same problems with mine. Only solution that worked was to repair the wiring loom using new plugs. The cause was very corroded connections on the 2 pin plugs on the injection loom. These did not show up with ohm meter testing. The problem only existed with a load on the wiring (when running) so only showed up on a scope with a current clamp to test each injector individually.

Hope this helps,

 

Paul.

Andy P,

Ok, I'll put this in as soon as I get in tonight. Are we sure there will be no side effects to adding it to half a tank or fuel ?

Paul C,

Right, I'll be giving this a shot tonight then.

Other Paul,

Already replaced the injector connection (thanks again Andy P for the spare part).

FWIW stu - the fuel inj cleaner we use can be used neat on problem vehicles, not sure about STP but putting it in 1/2 tank should be fine. :)

Try a noid light on that injector feed. Unplug the injector loom plug from the injector and insert noid light into plug.

Start the engine and see if the light is flashing (with the engine revs) or if it is off completely or on completely.

You can buy a whole set of noid lights for about £6 from Partco, I swear by them.

Hope you have some luck in fixing your problems.

Paul

Ok guys, really appreciate your help. But I did some tests today.

 

I've bypassed the Traction Control and the results are:

 

0.4 Ohms from the ECU side (disconnected) to the Injector connector (disconnected).

 

The injector itself is 13.8 Ohms across.

 

Which pretty much tells me that it either a badly clogged injector or the injector itself is screwed.

 

I'm going to wait till I finish my tank of petrol which had about 4 lots of injector cleaner in it. Then if I still don;t see any change, it looks like I'm going to have to book it in.

 

Some people say that you can dremel the front part of the Plem to reach the front screw holding the injector in. Is this a wise move ?. Shall I have a go myself or would you reccomend doing it the propper way ?

 

P.S.

Paul C, Thanks for your over the phone help today.

Just changed back to my old PTU hoping it may be that. But I still have the same problem.

 

John/Mike,

Have you got Al's number handy ?

I got a feeling I'mn gonna need to book this one in :(... I failed :(

Al number 01702 469800

 

If you need a after lift give me a shout.

Is there a way that you could wire that injector feed to another injector? That way you can see if the fault follows the injector or the feed from the ECU. Proving if it is an injector fault or a feed problem.

 

Good luck.

Paul

John, Thanks for the number mate, also what's an after lift ?.

 

Paul,

To do this I would need to take an injector from maybe chamber 4 and put it in chamber two to test. Although the injectors are universal I don't think I can just plug another injector connector from say number 4 onto this number 2 injector. Is this what you meant.

 

Can someone confirm that this can or can not be done ?

Originally posted by smw1

John, Thanks for the number mate, also what's an after lift ?.

 

 

 

You know one of them long things.

Right by a window ?